"We are stunned that RealNetworks has adopted the tactics and ethics of a hacker to break into the iPod, and we are investigating the implications of their actions under the DMCA and other laws, said Apple's statement. "We strongly caution Real and their customers that when we update our iPod software from time to time it is highly likely that Real's Harmony technology will cease to work with current and future iPods.

For its part Real Networks said customers have welcomed the introduction of Harmony.

"Consumers, and not Apple, should be the ones choosing what music goes on their iPod," Real Networks said in a statement given to MacCentral.

While Apple says they will investigate the implications of RealNetwork's actions under the DMCA, Real said they are following well established tradition of fully legal independent developed paths to achieve compatibility.

"There is ample and clear precedent for this activity, for instance the first IBM compatible PCs from Compaq," said RealNetworks. "Harmony creates a way to lock content from Real's music store in a way that is compatible with the iPod, Windows Media DRM devices, and Helix DRM devices. Harmony technology does not remove or disable any digital rights management system. Apple has suggested that new laws such as the DMCA are relevant to this dispute. In fact, the DMCA is not designed to prevent the creation of new methods of locking content and explicitly allows the creation of interoperable software."

Jupiter Research Senior Analyst Joe Wilcox was cautious on legal issues, but noted that Apple has other ways of dealing with RealNetworks.

"I assume Real wouldn't have taken the risk without confidence there would be no legal consequences," Wilcox told MacCentral. "However, there are always technological consequences.

Real reiterated their commitment to Harmony "and to giving millions of consumers who own portable music devices, including the Apple iPod, choice and compatibility."